Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005).  IAHS Publ. 310, 2007, 57-68.

 

Water Safety Plans: methodologies for risk assessment and risk management in drinking water systems

 

JOSÉ M. P. VIEIRA

Department of Civil Engineering, University of Minho, 4704-553 Braga, Portugal

jvieira@civil.uminho.pt

 

Abstract Worldwide, providing good and safe drinking water is considered to be a fundamental political issue for public health protection, and must be the primary objective of water supply systems. Drinking water quality control has currently been based on detection of pathogens and toxic concentrations of chemicals by means of monitoring programmes and compliance with national or international guidelines and standards, relying mainly on indicator bacteria and chemicals maximum concentration levels. However, this methodology is often slow, complex and costly. Even for sophisticated and well-operated systems these monitoring schemes have proved to be inefficient in preventing waterborne diseases, such as Giardia or Cryptosporidium outbreaks. From this evidence we can conclude that end-product testing is a reactive rather than preventive way to demonstrate confidence in good and safe drinking water. This justifies the need for the formulation of a new approach in drinking water quality control based on an understanding of system vulnerability to contam­in­ation and on preventive means and actions necessary to guarantee the safety of the water supplied to the consumer. The water safety plan is a concept for risk assessment and risk management throughout the water cycle from the catch­ments to the point of consumption. This approach includes the identification of the hazards and introduction of control points that serve to minimize these potential hazards, providing for more effective control of drinking water quality. This paper presents an overview of the first two years experience in developing and implementing a water safety plan in a Portuguese multi-municipal water company. Since key personnel have contributed to the assess­ment of hazards and evaluation of corrective actions for control points, a greater understanding of water quality control and improvements to the technical operation and performance have been registered, demonstrating good value for the methodology.

 

Key words  drinking-water quality; multiple barriers; risk management; source water protection